Recent Posts

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Beginners / Re: Need a (slightly) random signal ? Hers an idea, using CDS light sensor.

« Last post by RJSV on Today at 02:03:21 am »

My bad, as you STILL get the optical signal, so only need the CDS sensor....(stupid mistake, sorry).

   Also useful when experimenting with light sensing diodes ...

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Beginners / Need a (slightly) random signal ? Hers an idea, using CDS light sensor.

« Last post by RJSV on Today at 01:59:33 am »

   Hello there!
   After purchasing one of those cheap 'Garden Lamps' it was amusing to watch and contemplate the 'flicker' signal that gets generated.   It's a slow candle-like effect, that COULD be useful as an optical signal source...in this case as an informal signal gen.

   Simply couple your extra CDS sensor, that will be round, with glass front, and, usually, some visible track line grid.   I've found the sensor is good when placed as a replacement for single resistor, like in some 555 or Lm311, or Lm339 type oscillator circuit.
   The sensor usually is in range of about 500 ohms, so when putting in place of, say, 10 kohms, best to put about a 3k to 5 k in series, so you get around 10k, but with variations, according to light levels.
   The solar device LED, (I've assumed) is made to flicker, by some simple processor.
   OMG, ...??  Are the light flickers generated inside the output LED, itself ?

   In that case would need to put simple current monitor and LM324 OPAMP buffer, to follow the small current fluctuations.

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Projects, Designs, and Technical Stuff / Re: Vacuum Fluorescent Display Driver

« Last post by floobydust on Today at 01:58:50 am »

With power off, I would measure ohms and look for a short, on the HV rail and around the new 518 IC. If it bagged and is shorted, it would overload the DC-DC converter and possible its supplying rail. It might be why you see no filaments, although you said you measure 5.8VDC. I thought the DC-DC output AC to the filaments?

Once I had an Aliexpress special IC, lasted about 1 minute and cratered after a power down/up sequence. Thanks liaoxiyuan/SICSTOCK store for that waste of time.

The HV518 is susceptible to latch-up, they actually have a power up sequence in Sect. 3.2; The 5V rail must be the first to come up and last to go down, wrt VPP. I put a Schottky diode between the two rails to do this, but not something to do wrong and maybe your rail capacitance is low value. It's just a strange happening.

Worst case the VFD has an internal low resistance or short, since the 518 is push-pull output, it could roast if two outputs arm wrestle each other. Does that make sense? Any solder bridge between two outputs could do that as well.
You can check ohms at the display pins, as if adjacent on the 518.

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Microcontrollers / Re: Has anyone used ASAN & MSAN, and relevance to embedded arm32

« Last post by SiliconWizard on Today at 01:56:56 am »

Note that FreeRTOS has stack checking features, if you use it: https://www.freertos.org/Stacks-and-stack-overflow-checking.html

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Projects, Designs, and Technical Stuff / Re: 3D printing company similar to PCBWAY for circuit board

« Last post by SiliconWizard on Today at 01:54:05 am »

Note that an alternative to 3D printing for small-series plastic enclosures, often overlooked, is plastic machining. Some companies offer custom enclosures this way, like: https://www.polycase.com/customized-enclosures
Of course you'll have to pick from existing shapes, but after that, there's some amount of customization possible.
The result is usually much better looking than 3D printing and more durable.

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Test Equipment / Re: Siglent SDS2000X Plus - Bugs / Missing Features / Feature Requests

« Last post by KungFuJosh on Today at 01:52:32 am »

I'm into the habit of winding back brightness to 80%.......for no good reason other than not needing full brightness.

Do you have any idea about my question: Is there a reason the screensaver doesn't shut off the backlight?

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Test Equipment / Re: Siglent SDS2000X Plus - Bugs / Missing Features / Feature Requests

« Last post by BillyO on Today at 01:50:27 am »

I'm into the habit of winding back brightness to 80%.......for no good reason other than not needing full brightness.

I'm a 50% guy.

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Beginners / Re: uCurrent Gold Schematic

« Last post by floobydust on Today at 01:49:16 am »

I thought the nA shunt 10k is simply left in-circuit all the time, no need to switch it in with a mosfet 
I wonder why the MAX4239 isn't just one stage with AV=100 instead of two parts AV=10. The bandwidth is still high enough for most needs.
Any protection/clamp TVS etc. has leakage current and must be carefully thought out.

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RF, Microwave, Ham Radio / Biquad yagi design?

« Last post by cadr on Today at 01:45:03 am »

Does anyone have any references to designing Biquad Yagi antennas?

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Test Equipment / Re: Siglent SDS2000X Plus - Bugs / Missing Features / Feature Requests

« Last post by tautech on Today at 01:42:07 am »

I'm into the habit of winding back brightness to 80%.......for no good reason other than not needing full brightness.